The present invention relates to the field of coherent light amplifiers.
Of the two general method of Raman beam combining, namely dichroic beam splitting mirrors, and angular multiplexing, angular multiplexing is attractive since the separate pump and seed beams can follow separate paths through the Raman cell. Unfortunately, the Raman process is "imperfect" for geometries in which the pump and seed beams are not collinear. For these cases, the relative tilt between the pump beam and the seed beam can generate, in the simplest geometries, a wavelength-dependent tilt on the amplified wavefront of the seed beam output. The amount of the unwanted seed beam tilt can be approximated by ##STR1## where .DELTA..lambda. is the bandwith of the broadband pump of wavelength .lambda. and Tilt/pump is the relative angle between the pump beam and the seed beam. This effect is not correctable with conventional beam control techniques and can be significant.